[lxc-users] Fedory 20 LXC fails to start on Ubuntu 14.04 host?

[Robert Pendell]

On Sat, May 24, 2014 at 9:29 PM, Michael H. Warfield wrote:
> On Sat, 2014-05-24 at 22:00 +0200, Timotheus Pokorra wrote:
>> Hello Mike,
>
>> > 1) Are you running this container unprivileged?
>> I checked what it means to run a container unprivileged. I think I run
>> it privileged, I am logged in as root on the host machine, and I am
>> just trying to start with lxc-start -n myFedora.
>
>> > 2) Have you tried creating the container using the -t fedora template?
>> I tried lxc-create -t fedora -n myFedoraTest
>> Unfortunately, the result is the same.
>
>> >> Anyone any ideas?
>> >
>> > The error the OP was showing was a SEGV (11) in systemd.  He did not
>> > specify how he created the container, or how he was running it (priv /
>> > non-priv).  A SEGV in systemd would be pretty serious.  It would seem to
>> > be an executable conflict at a pretty deep layer.  I guess it would also
>> > be good to know what the host kernel version is as well.
>> I indeed get the exact same output as the OP.
>
>> On the host:
>> uname -a
>> Linux j80074.servers.jiffybox.net 3.2.0-60-virtual #91-Ubuntu SMP Wed
>> Feb 19 04:13:28 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
>
>> The LXC host (Ubuntu) is a virtual machine running in a XEN environment.
>> I would understand if that is not possible, but it is possible since
>> Debian 7 and CentOS 6 containers run fine on this host.
>
> XEN???
>
> Oh crap...  It's information like this that is critical to understand
> what's going on.
>
> You're in an environment with a Fedora 20 container running on an Ubuntu
> virtualized host in a Xen guest running under a Xen paravirtualization
> hypervisor.  Without knowing this, it would be impossible to even guess
> where the problem may lay (even with this information, it may be
> impossible).  I haven't even begun to attempt to reproduce it but the
> number of independent variables just shot through the roof.
>
> First order of troubleshooting.  Eliminate independent variables...
>
> Have you attempted running a Fedora container on an Ubuntu host running
> on raw iron?  If not, you need to do so and report those results.
>
> I haven't screwed with Xen in years but all HW and para virtualization
> requires some instruction emulation back in the hypervisor.  This could
> easily be some incompatibility between the Xen hypervisor in supervisory
> state and emulating some instruction that systemd is requiring.  I can't
> even begin to reproduce your environment at this point with Xen in the
> loop.  You really need to simplify this into a basic install with basic
> containers and try running it that way.  This could be a problem in the
> Xen hypervisor, it could be a problem in the Xen guest virt drivers, it
> could be in systemd that never expected to run in a container in a guest
> under Xen.  I can't tell.
>
> In the upcoming week, I'll look into firing up an Ubuntu server, since I
> now have a free Dell tower now that I've virtualized my NST development
> engines into LXC containers.  I don't even want to THINK about doing
> Xen.
>
> You've got to simplify that environment in order to isolate the origin
> of the problem.
>

I took a try at this earlier and it worked fine.  I did a full install
and boot for Fedora 20 amd64 using "lxc-create -t download -n test" as
root.  Here is my environment.

Host: Linode
Kernel: 3.14.3 (host supplied)
Technology: Xen Paravirtualized

Xen Hypervisor Mode (HVM) shouldn't be much different than KVM however
I have not used each of them enough to know for sure.